JPH022655A - Method and apparatus of cooling integrated circuit package - Google Patents

Abstract

PURPOSE: To make soldering between the external connection pad of an integrated circuit package and the conductive path of a substrate to be certain and to use the substrate as a heat radiation body, by soldering the base of the integrated circuit package on the upper surface of the substrate, and soldering a specified peg on the lower surface of the substrate. CONSTITUTION: A thin plating coating area 24 for soldering is provided on the external surface of the base of an integrated circuit package 14. Two tin plating coating areas 32 and 33 which are mutually connected through a coating through hole 31 are provided on both faces of a substrate 10. The base of the integrated circuit package 14 is soldered on the upper surface of the substrate 10 so that the tin plating coating areas 24 and 32 face each other, and a peg 40 is soldered on the lower face of the substrate 10. The peg 40 has a solder plating surface 41 and it has a hole constituted of a passage whose one end terminates at a capillary tube 42 opened into the tin plating coating surface 41 and whose other end terminates by a solder reception part 43. The passage absorbs excessive solder with the base of the integrated circuit package 14 of the substrate 10 via the coating through hole 31.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to cooling integrated circuit packages, particularly packages intended for surface placement in hybrid circuits. The hybrid circuit uses a plain J1. Electronic components can be assembled with high component density on a rigid support. The substrate is a hardened ceramic plate coated on one or both sides with a printed network of resistors and conductive tracks;
The network is optionally protected by a vitrified insulating layer, and conductive paths lead to pads which, once attached, serve to connect the hybrid circuit components and pins to external devices.

Integrated circuit packages used for this type of purpose in the Beimen era were usually in the form of a ceramic cup, which was closed with a metal lid and had external connection pads around its exterior for surface placement purposes. The pad fasteners connect to the internal connection pads via a supply line passing through the wall of the cup. Internal connection pads connect to the integrated circuit chip, which is secured to a metallized area provided inside the cup and secured by brazing or soldering at its bottom.

One example of a method for cooling this type of integrated circuit package is to glue or snap a heat dissipating metal part to the outside of the bottom of the ceramic cup in direct thermal contact with the integrated circuit. Place the package upside down on top of the hybrid circuit. A disadvantage of this approach is that the mass of the radiator must be supported by the integrated circuit package, making it more fragile and making the soldering between the external connection pads and the four circuits on the board more fragile. The drawback of this is that it does not use the substrate as a heat dissipator, and at the same time it increases the height of hybrid circuits that are commonly installed in printed circuits.

The present invention is to eliminate these drawbacks.

SUMMARY OF THE INVENTION The present invention is a method of cooling an integrated circuit package for placement on a substrate, the method comprising: attaching a tin plate to the bottom outer surface of the integrated circuit package suitable for fixation by soldering; C) A coating area is provided in the zone where the peripheral circuit package is to be located, and the base board is provided with two tin-covered areas on both sides of the base board, one over the other, the first tin-covered area being placed on top of the other. is disposed opposite a tin plated coating area on the bottom of the integrated circuit package, and the second tin plated coating area is connected to the first tin plated coating area through at least one coating through hole through the substrate.
Furthermore, the plated areas on the bottom of the integrated circuit package are placed face to face. The integrated circuit package and solder are mounted at the lower level of the substrate, and the peg has a tinned surface such that it can be attached to the second tinned coating of the substrate. and the peg is perforated by at least one metal hollow passageway terminating at one end in a capillary opening into the serrated coating surface and terminating at the other end in a solder receptacle; In this method, the solder passage serves to absorb excess solder between the substrate and the integrated circuit puncture through the coating through-holes.

If the board is sufficient to dissipate the heat generated by the integrated circuit package, the pegs can be placed with only a small contact area with the board, so that after soldering the pegs can easily separate and Excess solder between the bottom of the integrated circuit package and the board is absorbed, simply by breaking the solder that secures the pegs to the board.

The invention also provides a cold brew apparatus for carrying out the above method.

If the pegs are not removed, the board will become wedged between the integrated circuit package and the heat dissipating metal pegs. This prevents mechanical forces from being transferred from the peg to the soldering connections at the integrated circuit package or its external connection pads. In addition, whether the cooling of the integrated circuit package is carried out either on the board itself or by means of metal pegs soldered underneath the board, the entire hybrid circuit is primarily placed on a printed circuit. It is possible to make the size smaller than 8. This is because the pegs fit into holes in empty spaces that would otherwise be provided in the printed circuit.

Brazing an integrated circuit package to a substrate provides much improved thermal contact between the package and the substrate compared to adhesive or fill-in snap fasteners.

However, this type of assembly suffers from the problem of over-solder,
This occurs because it is difficult to control the direction of the deposited solder during the 1!2 stacking operation. The result of this is that the integrated circuit package is at an inappropriate height relative to the board, thus preventing the solder between its outer connection pads and the pads on the board's conductive tracks, or between the various pads. This problem can be solved by soldering the bell over the package at the same time as placing a solder on the other end of the board, in which case one or more Excess solder is sucked through the sheathing perforations due to surface tension acting on the solder in the capillary portion of the passageway, while the solder maintains good thermal contact between the integrated circuit package and the peg. .

Embodiments of the present invention will be better understood with reference to the drawings in Attachment A4.

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a hybrid circuit which combines a substrate 10 supporting a printed network of conductive tracks 11 leading to tin plated connection pads 12 on which electronic components 13 are disposed. It also includes connections to the integrated circuit package 14 and terminal pads 15, which include soldered electrical connection pins 16 for externally connecting the hybrid circuit.

The substrate 10 is a thin ceramic temporary, and its negative side or both sides are coated with a low antibody and conductive path 11 by a silk screen printing method.
covered by a network of The network is optionally protected by a vitrified insulating layer (not shown), with the exception of connection pads 12.15, which are left accessible for tinting purposes.

The integrated circuit package 14 for the surface device is an elongated ceramic cup 2 that is closed by a metal cap 21.
J3 in the shape of a 0, and around its periphery are external connection pads 22 extending under the package in the form of a rectangular contact area 23 shown in FIG.

Each pin 16 has a head 17. The head is fitted onto the edge terminal pad 15 via a pawl to be placed on the edge of the board. The pins extend perpendicular to the substrate 10, allowing the hybrid circuit to then be placed on the larger area of the mark 11 circuit, but the hybrid circuit will be located slightly above the printed circuit.

The hybrid circuit components are assembled using conventional "reflow" techniques that consist of bonding the board 10 while it is bare. According to it, connection pad 12.
15, place a pin on the component or board 10 with its own connection band in contact with the solder patch on the pad of the board 10, and bond them with adhesive or... held in place via temporary support means;
The assembly is then heated to solder all of the components and pins simultaneously until the solder strips on the board melt and the solder migrates by capillary action onto the pads of the components and onto the pin tabs.

In addition to the usual electronic components, a frusto-conical metal peg 30 forming a heat dissipator is placed under the bottom surface of the substrate 10 of the circuit package 14. In between, this metal peg is soldered to the substrate 10 simultaneously with the bottom of the integrated circuit package 14, and other components are also soldered thereto.Soldered with respect to the peg and package are three tinned sheaths. (not visible in Figure 1), one of which is integrated circuit package 1
4 at the center of its bottom outer surface; the other two are at coincident positions on both sides of the substrate 10.

FIG. 2 shows the bottom exterior of the rectangular cup that constitutes the integrated circuit package 14 and includes a rectangular contact area 23 around its periphery. The contact area extends to the outer connection pad [S22, which pad is received in the side wall of the cup and connects to the connection pad 12 on the substrate.
to be soldered. The center of the cup includes a tinted covering area 24, shown in this case as a circle, which is electrically insulated from the rectangular contact area and which allows the bottom of the cup 20 to be soldered to the substrate 10. It is something to do.

FIG. 3 is a cross section of the substrate at the position of the covering through hole 31.

The hole is approximately centrally positioned to receive integrated circuit package 14. The figure also shows a side view of the integrated circuit package 14 above the substrate 10 and a cross section of the heat dissipating metal peg 40 below the substrate.

Substrate 10 is shown tinted. On its side adjacent to integrated circuit package 14 , the substrate has connection pads 12 facing the intersection between rectangular contact area 23 of integrated circuit package 14 and external connection pads 22 .

In the center of the connection pad 12 forming the perimeter of the rectangle (
It has a tinted covering area 24 on the bottom of the facing package 14 and a tinted covering area 32 corresponding in shape and size. The opposite side of the substrate 10 facing away from the integrated circuit package 14 has another tinted coating area 3.
3, and this region communicates with the first region 32 via a sheathing through-hole 31 and optionally through other sheathing through-holes, depending on the dimensions of the regions 1 and 32 and 33. By tinting, the coating through-hole 31 is filled with solder, and each of the connecting pads 12 and the tinted coating area 32,33 is soldered to the tinned coating area 33 (in this case circular) of the board 10 at the solder piece 35°41. be done. The peg is provided with an axial passage through one capillary tube 42 to the bottom surface 4.
1, and the tube opens in the vicinity of the coating penetration 31 in the substrate 10, and the passage, on the other hand, opens close to the opposite bottom surface;
It leads to a solder receptacle 43 having a larger diameter than the capillary tube.

During the reflow operation, integrated circuit package 14 and heat dissipating pegs 40 are pulled over tinted coverage area 32°c.

Since the aged VA peg has been pre-treated with a suitable cleaning flux, the excess solder contained in the pieces 36,37 will be sucked out due to surface tension phenomena by the capillary section 42 of the passage through the peg, as shown in FIG. It now occupies a position within the receiving part 43. This causes the integrated circuit package 14 to be pressed tightly against the substrate surface, and the rectangular contact order VA23 of its external connection pads all come into contact with the solder strips 35 on the connection pads of the substrate 10, so that the connection pads The pegs appearing between the pads and the tinted covering area 24 or 32 are of small diameter with a small area of the bottom surface and are therefore soldered properly in all cases, so that the integrated circuit package 14 The heat generated from the substrate 10
If the soldering to the 1.4 board 10 is sufficient on its own to release the rll, the connection is brittle and easily broken.

Figures 6, 7 and 8 are another type of cylindrical or frusto-conical heat dissipation pegs. These are perforated with one or more passages with an angle σ It is possible to occupy the peg face furthest from the substrate, thus leaving freedom for processing, e.g. with means of fixing the heat dissipation plate for increased radial area.

FIG. 6 shows a cross section of a cylindrical heat dissipating peg 50 for soldering to the V-plate 10 through the bottom surface 51. The peg 50 has four angled passages (three of which are visible) with a capillary section 5 opening into the bottom surface 51 at the corner of the square.
2.53 or 54, and each has a side-opening T-shaped receptacle 55.56.57. A threaded hole 58 is drilled in the bottom surface 51- of the peg furthest from the substrate, and a maturing 1 table plate 59 is formed.
Receives screws 58- for fixing.

7 and 8 are perspective views of a truncated conical heat dissipation peg similar to that seen in FIG.
It is designed to be soldered.

The pegs 30 of FIG. 7 are similar to those secured to the hybrid circuit of FIG. The peg has a branch passage through it, with a preliminary passage 61 opening at the outer end of the base 62 for soldering to the board 10, and a plurality of branches 64, 65 opening into the side walls of the peg. .66°67, said passageway 61 intersects at right angles to a chamber 63 and opens at its inner end, and said branch forms a solder receptacle. The peg 70 of FIG. 8, like the peg of FIG. 6, is bored with four angular passages, each parallel to one sleeve of the truncated cone.
, 72, 73, 74, each of which opens into the small bottom surface 75 at each of the four corners of the d quadrilateral, and each passage is
Solder receptacles 76, 7 that open at right angles to the axis of the truncated cone and along the sides. .

78, 79.

Without departing from the spirit of the present invention, the arrangement of the scales could be changed and the scale means could be replaced by a drawing means. In particular, the heat dissipation pegs can also be provided with fins or grooves, as is usual in half-cotton radiators, as a function of requirements and external surface. The face of the peg remote from the substrate can also have fixing means other than threaded holes, which can be rivet bolts or threaded shanks. Therefore, the disadvantage of removing the object 7 electric from the peg,
That is, the thermal conductivity of the peg and the effects of inert attachments can be avoided to a large extent.

[Brief explanation of the drawing]

1 is a partially cutaway schematic perspective view of a hybrid circuit equipped with an integrated circuit package arranged using the cooling device of the present invention; FIG. 2 is a perspective view from below of the integrated circuit package of FIG. 1; FIG. 4 is a partial sectional view of the integrated circuit package and the cooling device according to the present invention before being soldered to the substrate; FIG. 4 is a partial sectional view of the integrated circuit package and its cooling device after being soldered to the substrate; Figure 5 is a perspective view of the cooling device shown in Figures 3 and 4, and Figure 6 is a perspective view of the cooling device shown in Figures 3 and 4.
, a sectional view of a modification of the cooling device shown in FIG. 5, 10...
...Substrate, 11...Low antibody and 4 electric circuits, 14.
...Integrated circuit package, 16...Pin, 30, 40.50.70...Heat dissipation peg, [
34,67...Aisle. Hi Confident

Claims (9)

[Claims] (1) A method of cooling an integrated circuit package for placement on a substrate, which method comprises: providing a tin-plated coating area on the bottom outer surface of the integrated circuit package suitable for fixation by soldering; In the zone where the circuit package is to be located, the substrate is provided with two tin-plated areas superimposed on each other on both sides of the substrate, the first tin-plated area being the tin-plated area on the bottom of the integrated circuit package. the second tin-plated coating area is in communication with the first area through at least one coating through-hole through the substrate; The plating areas are soldered to the top of the board in a face-to-face manner, and the pegs are soldered to the integrated circuit package at the bottom level of the board, with the pegs bonding to the second tin plating area of the board. the peg has at least one end terminating in a capillary tube opening into the tin plating surface and the other end terminating in a solder receptacle; A method in which one metal wall is perforated by a passageway, said passageway serving to absorb any excess solder between the substrate and the bottom of the integrated circuit package through the coated through-holes to each other. (2) The peg is in contact with the board through a small area so that the connection to the board by soldering is fragile, and furthermore, after soldering to the board, the peg separates from the board by mere breaking. The method according to claim 1. (3) an apparatus for cooling an integrated circuit package for placement on a substrate, the device comprising: soldering the integrated circuit package together with the bottom of the integrated circuit package at a common location on both sides of the substrate through tinted coating areas disposed on each of the sides; heat dissipation pegs attached thereto, the tinned coating areas of the substrate are in communication with each other via at least one coating through hole, and the heat dissipation pegs are arranged adjacent to the substrate. 2. A device perforated by at least one metal wall passageway terminating at one end by a capillary tube opening into the opening and at the other end by a solder receptacle. (4) The heat dissipation peg comprises a capillary tube opening into the surface facing the substrate and a solder receptacle opening into the side surface of the peg to avoid occupying the surface of the peg facing away from the substrate. 4. The device of claim 3, wherein the device is perforated by a passage having at least one angle. (5) said heat dissipating peg is located in a chamber at the intersection between a plurality of branches that open to the outside of the peg on the side facing the substrate and on the other hand form solder receptacles and open into the sides of the peg; 4. The device of claim 3, wherein the device is perforated by a branch passageway containing a capillary tube opening into the interior of the peg. (6) the heat dissipation peg has a plurality of angled passages with the outer ends of the capillaries opening at the corners of the square on the side of the peg facing the substrate and with the solder receptacles opening around the sides of the peg; 5. The device of claim 4, wherein the device is perforated. 7. The apparatus of claim 3, wherein the heat-dissipating peg has securing means on a surface facing away from the substrate, the securing means securing the peg to the heat-dissipating plate. 8. The apparatus of claim 3, wherein the heat dissipation peg is cylindrical. 9. The apparatus of claim 3, wherein the heat dissipation peg is frustoconical.